Actuator magnet assembly



Sept. 5, 1961 w. BREITLING ACTUATOR MAGNET ASSEMBLY Filed Sept. 15, 1959 lNVEN TOR.

W/L HEL M 595/ ru/va La {QM PATENT AGE/V7 2,999,193 ACTUATOR MAGNET ASSEMBLY Wilhelm Breitling, Wilhelmshaven, Germany, assi'guor to Olym ia Werke A.G., Wilhelmshaven, Germany Filed Sept. 1-5, 1959-, Ser. No. 840,050 Claims priority, application Germany Sept. 24, 1958 3 (Claims. (Cl. 317191) The present invention relates to an actuator, magnet assembly having particular utility in the communication technique.

Different kinds of magnet and armature assemblies of the plunger type have been known. Their cylindrical or prismatic armatures are surrounded by correspondingly shaped magnet pole pieces and are biased in rest position by springs.

The known armature and magnet assemblies are not suited to solve certain switching and actuating problems in spite of their advantages, due to the small leakage in the air gaps, because the suspension of the armature and the shape of the pole pieces necessary for operation are not optimum for the solution of these particular probev lems.

Also, various types of magnets with bar-type armatures have been known which are generally suitable for switching and actuation. In contrast to the plunger-type armature, the air gap leakage of the bar-type armature is very large, so that the expense of the winding and the iron body is; higher for the same actuating force.

It is an object of the present invention to provide an electromagnet with a plunger-type armature and with a States Patent magnet coil having an internal opening with an air gap disposed in such a manner, that said armature can be pivotally mounted about an external pivot point and can be swung into the opening of said magnet coil.

It is another object of the invention to provide the electromagnet in such a manner, that the leakage in the air gap between the plunger armature and the magnet is very low. The suspension or mounting of the armature at its pivot point enables a long attraction path and, thereby, makes this magnet usable for switching and actuating, in cases where otherwise only bar-type armatures could be used.

Still further objects and the entire scope of applicability of the present invention will become apparent from the detailed description given hereinafter; it should be understood, however, that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.

In the drawings:

FIGURE 1 shows in perspective a first embodiment of an electromagnet and armature assembly according to the invention, parts of the magnet coil being broken away;

FIGURE 2 is a perspective fragmentary view, illustrating schematically the iron frame used when several assemblies according to the embodiment of FIGURE 1 are assembled together on a common base;

FIGURE 3 shows a side view of the assembly according to FIGURE 1, but having a modified air gap profile, parts of the structure being shown in section;

FIGURE 4 shows a side view of a further modified assembly in an illustration similar to that of FIGURE 3.

In the embodiment illustrated in FIGURE 1, an armature 1 is pivotally mounted about a pivot 2, said armature being a plunger having a T-shaped transverse cross section with the lower portion 4 of the T lying along the axis of a winding coil 3, the upper web portion of the armature being shown at 13. Due to this form of cross section, the structural height of the magnet can be decreased without decreasing the cross sectional area of the permeable material carrying the magnetic flux. The armature 1 forms in its longitudinal direction a long narrow rectangle resulting in a narrow width of the magnet. An iron pole piece 5 and an iron frame 6 formthe opposite, member of the iron path which is likewise T shaped in cross section, corresponding in shape and size to the armature 1. This armature 1 has a lug portion 7 (see FIG- URE 2) which is. rotatably mounted in a forked yoke member 8 which is spaced from the rear edge of the pole piece 5 by the width of the winding 3 (FIGURE 1). To transmit the armature movement to the part to be actuated, a coupling member 9 preferably of non-magnetic material, such as brass, is provided at the end of the armature opposite the pivot point 2. The armature may be retained in its rest position by means of a spring (not shown), said spring attaching to any desired point of the swingable armature.

A winding form 10 is provided on the iron pole piece 5 and'is of similar shape. This winding form should be made of sufiiciently strong material to avoid damages by the moving armature due to wear, or should be provided with a strong lining 11. The electrical winding3 is wound on the form 10.

It is agreat advantage of the magnet assembly shown in FIGURES 1 and 2 that the operative air gap of the movable armature having a long operating stroke is concentrated within the winding form. As a result of this, the magnetic leakage is substantially decreased and thus also the electrical energy required for the attractionof the armature. The winding can be made correspondingly less powerful so that a smaller width of the oblong armature and winding can be used.

In view of the narrow width, it is possible to assemble a plurality of these magnets side by side and to combine them in a component having very small dimensions. For this purpose, an iron frame 6 is designed as a base on which the individual stationary cores 5 are assembled side by side. As yoke portion, a single piece 8 is suitably used into which slots are cut receiving the individual armatures and in which the latter are rotatably mounted on a common pivot shaft 2'.

In contrast to the known armature magnets, the height of the operative air gap in the open position of the armature is not constant over the length of the armature. The portion of the armature closer to the pivot point 2, 2' has a smaller spacing from the pole piece 5, while the portion remote from said pivot point has a larger spac ing. Therefore, the characteristic curve of the attracting force along the gap is diiferent in case of the assembly according to the invention than in the known plungertype armature assemblies. When the current is passed through the magnet winding, there appears a larger attraction force close to the pivot point than would appear in case of a constant height of the air gap. By changing the shape of the air gap over the length of the armature, the characteristic of the attraction force over the stroke can be varied in the assembly according to the invention. Thus, the characteristic of the attraction force of the as sembly can be adapted to different kinds of operations when the magnet is used as an actuator.

The embodiment of FIGURE 3 shows a suitable contour 15 of the pole pieces to provide a modified air gap. By extending the iron pole piece 5" upwardly, as compared with the iron pole piece 5 in FIGURE 1, an improved support for winding form 10 is obtained. If such extension is not possible, guide members (not shown) may be secured, for example, to the narrow base of the frame 6 to obtain a superior coil mounting.

In view of the fact that the operative air gap of the magnet according to the invention is entirely within the winding, magnetic influence of an adjacent magnet is prevented even when the magnets are assembled side by side with only small separation, as is the case with a series arrangement of bar-type assemblies.

,A further advantage of the assembly'according to the invention over the known plunger-type armature assemblies resides'in the manner of armature displacement. Since the conventional plunger-type armature performs a purely linear motion in the direction of the coil axis, jamming between the armature and winding readily occurs, 'sothat the armature has to be very accurately manufactured, which results in an expensive design and manufaeture. This disadvantage is overcome by the invention because, due to the rotational mounting of the present armature, satisfactory guiding of the armature into the opening of the winding is assured.

As a result of the'shape of the iron body according to the invention, a substantial simplification in mass manufacture of assembly groups is obtained. The armatures, yokes, and cores can be punched from iron sheets and can be joined by riveting or similar methods conventional in mass manufacture. a

A further embodiment of the invention is shown in FIGURE 4. In place of the pin-type pivot mounting for the armature shown in FIGURES 1 to 3, FIGURE 4 provides a knife edge bearing 12 on the upper surface of the frame 14, whereby the bearing friction is substantially reduced with respect to the friction of a pin type pivot, ,as shown in FIGURES l to 3. Furthermore, armature frictionwithin the opening which may be increased by the magnetic flux is also excluded in the embodiment of FIGURE 4 while, at the same time, the extent of the edge at 12 prevents lateral tilting of the armature.

I claim:

' 1. An aetuatormagnet assembly comprising, a frame;

a long narrow pole piece fixed on said frame, said frame and pole piece being arranged to form a stationary structure which is T-shaped at cross sections taken normal to the longer dimension of said pole piece and the entire T-shaped structure being made of permeable material; a winding having an axial opening therethrough snugly fitting over said pole piece and the winding extending thereabove; an armature above said winding and having a pole piece extending into the winding and similar in length and width to the fixed pole piece, said armature being T-shaped at cross sections taken normal to the longer dimension of its pole piece and the entire T-shaped portion being made of permeable material; and pivot means rotatably'conneoting the armature to the frame beyond said winding and transversely of the longer dimensions of said pole pieces.

2. In an assembly according to claim 1, the air gap as measured with the armature pole piece separated from the fixed pole piece changing longitudinally thereof in a manner linearly increasing in the direction away from said pivot means. 7

3. In an assembly according to 'claim 1, said pivot means comprising a yoke standing upwardly from said frame parallel with the axis of the winding and having a groove extending transversely across the yoke on the side toward the winding, and said armature having a knifeedge engaged in said groove and forming therewith a pivot for the armature.

References Cited in the file of this patent UNITED STATES PATENTS 2,738,451 Bachi et al. Mar. 13, 1956 

